Process of making persulfate of sodium.



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AUGUSTE LUMIERE AND LOUIS LUMIERE, OF LYONS, FRANCE.

PRQBESS OF MAKING P ERSULFATE OF SODIUM.

SPECIFICATION forming part of Letters Patent No. 659,820, dated October16, 1900.

' Application filed January 31,1900. Serial No. 3,497. (No specimens.)

To all whmn itvitcty concern:

Be it known that We,AUGUSTE LUMIERE and LOUIS LUMIERE, citizens ofFrance, residing at Lyons, Monplaisir, France, have inventedImprovements in the Manufacture of Persulfate of Sodium,of which thefollowing is a full, clear, and exact description, and for which we havemade application for patent in Great Britain, dated the 18th ofDecember,1899, and in France, dated the 21st of December, 1899.

In his study and experiments relative to persulfuric acid and thepersulfates Marschall has not succeeded in isolating the persulfate ofsodium. According to this author the electrolysis of solutions ofsulfate of sodium would give persulfate, but the great solubility ofthis salt has prevented him from isolating it.

We have succeeded in preparing and isolating the persulfate of sodium bytreating the persulfate of barium by the sulfate of sodium. Thepersulfate of barium is employed in saturated solution. With it is mixedsulfate of sodium finely pulverized or in saturated solution. When themixture of the solutions or of the bodies in equimolecular proportionsis finished, the sulfate of barium formed is eleminated by filtering andthe process is finished by crystallization by natural evaporation inreceptacles having an extensive surface. Small crystals of persulfate ofsodium are soon deposited, which are collected, dried, and high dried ata rather low temperature. The evaporation and drying are efiected morerapidly and more certainly in cacao, but may nevertheless be effected atthe ordinary pressure and in the open air. Again, the persulfate ofbarium in saturated solution can be treated with a correspondingquantity of sulfuric acid, the mixture being intensely cooled to obviatethe decomposition of the persulfuric acid formed. There is then added,in small portions and avoiding any heating, either soda or carbonate orbicarbonate of soda, either in the solid state or in a state ofsolution. When the persulfuric acid is saturated, it is filtered toeliminate the sulfate of barium. Then it is evaporated as beforedescribed with respect to the preceding method.

The persulfate of sodium thus prepared is in the form of small anhydrouscrystals very soluble in water, one hundred parts of water dissolvingfifty-three parts of persulfate of sodium at 25. It is applicable inindustry as an oxidizer or decolorizer and as an antiseptic.

Having fully described our invention, What we claim and desire to secureby Letters Patent, is-

The preparation of persulfate of sodium by means of persulfate ofbarium, by treating this body in very concentrated solution by thesulfate of sodium, after a preliminary treatment by sulfuric acid; thesolutions of persulfate of sodium thus formed being filtered andevaporated at a slightly-elevated temperature, substantially as hereinset forth.

In testimony whereof we affix our signatures in presence of twowitnesses.

AUGUSTE LUMIERE. LOUIS LUMIERE.

Witnesses:

THOS. N. BROWNE, GASTON J EANNIAUR.

